Bacterial soft rot is one of the most common and most destructive plant diseases – caused by particular species of bacteria, one of which is Pectobacterium. In a study published in the Archives of Phytopathology and Plant Protection, researchers tested the ability of spent green tea (SGT) extracts to protect carrot plants from soft rot caused by Pectobacterium.

In a time-kill assay, the researchers determined that when administered with the minimum inhibitory concentration (MIC) of SGT extracts, Pectobacterium died within 24 hours. This period shortened to just 18 hours once the amount of extract administered was 10 times the MIC.

Treatment with SGT was found to cause a significant reduction in pectin lyase (PL), polygalacturonase (PG) and pectin methylesterase activity in the carrots. The treatment also caused a low degree of maceration and relative electrolyte leakage.

However, the treatment did not decrease the carrots’ beta-carotene content, phenolic content and total antioxidant percentage.